Engine Control Instrument

CONTROL LINES TOENGINE____/

GOVERNOR 1 FREE-AIR UNLOAOER *

Fig. 6.23. Aerated mud system. After Bobo, Ormsby, and Houch,42 courtesy Oil and Gas Journal.

(2) greater safety: quick weight buildup is quickly obtained by shutting off the injected air. Explosions and/or fire possibilities are minimized by the water in the mixture.

A typical layout for this method is shown in Figure 6.23. Air is injected into the system between the mud pumps and the standpipe. The air-mud ratio may be controlled by increasing or reducing inputs of each fluid. Such a system is highly versatile and offers considerable promise in some areas. All air, all mud, or any mixture in between may be obtained.

Low solids, low viscosity muds are the best for this purpose, as they are most easily de-aerated in the pits. Foaming and emulsification of muds are undesirable, since the high compressibility of such mixtures makes mud pump operation very inefficient. Drill string corrosion may be controlled by using saturated lime water in the drilling mud.

A further discussion of these techniques will be presented later, when we consider the factors affecting rate of penetration. Air and gas and their variant, aerated mud, are being widely applied as special drilling fluids.

PROBLEMS

  1. Derive Eq. (6.4) from Eqs. (6.1), (6.2), and (6.3).
  2. The following are Fann Y-G meter measurements for a particular mud: i»™ = 20, $300 = 12.

Compute: (a) plastic viscosity, (b) apparent viscosity,

  • c) Bingham yield value, (d) true yield value. Ans. '
  • d) 3 lb/100 ft2.
  1. The corrected API (30 minute) filter loss of a water base mud was determined as 10 cc at a temperature of 86°F. What would it have been at 140°F? At 212°F? Ans. 14.6 cc; 18.8 cc.
  2. A mud exhibited a water loss of 5.0 cc in 10 minutes. Assuming no initial spurt occurred, what would be reported as the API filter loss? Ans. 8.7 cc.
  3. What would the 30 minute water loss of a mud be at 70°F if its corrected 15 minute water loss at 100°F was 8.0 cc? Ans. 9.5 cc.
  4. How much fresh water and clay must be mixed to prepare 1 liter of 1.05 sp.gr. mud? Ans. 83.2 gm. clay, 967 cc water.
  5. A fresh water-clay mud has a density of 9.0 lb/gal. Compute: (a) the weight percent clay in the mud (b) the volume percent clay in the mud. Ans. (a) 12.5%

8. (a) How many sacks of barite should be added to 500 bbl of the mud in Problem 7 to increase its density to 12 lb/gal?

  • b) How many gm per liter is this?
  • c) What is the resulting volume and weight percent solids in the 12 lb mud? Ans. (a) 945 sacks (b) 540 gm/liter
  • c) 16% by volume; 41.7% by weight.
  1. What will be the final density of an oil emulsion mud composed of 20% (by volume) diesel oil and a 10 lb/gal water base mud? Sp.gr. of oil = 0.75. .4ns. 9.25 lb/gal.
  2. An 8 X 16 in. duplex mud pump is operating at 50 strokes per minute. The mud system contains 1200 bbl of 10 lb/gal mud. It is desired to add sufficient water to lighten this mud to 9.5 lb/gal. Piston rod diameter = 2 in.
  • a) What volume of the original mud should be discarded to have the same final system volume?
  • b) At what uniform rate should the water be added in order to complete the operation in two cycles of the system? (Assume 90% pump volumetric efficiency.) Ans. (a) 359 bbl (b) 1.33 bbl/min.
  1. Show that for a given tc/dc, p„, and pm, a plot of turbulent slip velocity vs cutting diameter may be represented as a linear plot on log-log graph paper.
  2. Prepare a set of curves showing Vc vs dc for pm = 8, 12, and 16 lb/gal. Assume p, = 21.7 lb/gal (sp.gr. = 2.6) and tc/dc = 0.20.
  3. Assuming a desired upward cutting velocity of 50 ft/min, what should the annular mud velocity be if:

dc = 0.50 in. (max) pm = 12 lb/gal dc/tc = 0.20 p, = 21.7 lb/gal

14. A pilot test on a 600 cc mud sample indicated that 1.5 gm of starch gave the desired water loss. How much starch should be added to the 1800 bbl mud system?

REFERENCES

  1. "The History of Drilling Mud," Sec. 100 in Drilling Mud Data Book, Baroid Sales Division, National Lead Co.
  2. "Field Testing," Sec. 900 in Drilling Mud Data Book, Baroid Sales Division, National Lead Co.
  3. Training Course for Mud Engineers, Magnet Cove Barium Corp.
  4. Principles of Drilling Mud Control, Petroleum Extension Service, University of Texas.
  5. Rogers, W. F., Composition and Properties of Oil Well Drilling Fluids. Houston: Gulf Publishing Co., 1948.
  6. Beck, R. W., Nuss, W. F., and T. H. Dunn, "The Flow Properties of Drilling Muds," API Drilling and Production Practices, 1947, p. 9.
  7. Melrose, J. C., and W. B. Lilienthal, "Plastic Flow Properties of Drilling Fluids — Measurement and Application," Trans. AIME, Vol. 192 (1951), p. 159.
  8. Savins, J. G., and W. F. Roper, "A Direct-indicating Viscosimeter for Drilling Fluids," API Drilling and Production Practices, 1954, p. 7.
  9. Cardwell, W. T., Jr., "Drilling-Mud Viscosimetry," API Drilling and Production Practices, 1941, p. 104.
  10. Garrison, A. D., and K. C. ten Brink, "A Study of Some Phases of Chemical Control in Clay Suspensions," Trans. AIME, Vol. 136 (1940), 2nd reprinted ed., p. 175.
  11. Bingham, E. C., Fluidity and Plasticity. New York: McGraw-Hill Book Co., 1922.
  12. Burdyn, R. F., and L. D. Wiener, "That New Drilling Fluid for Hot Holes," Oil and Gas Journal, Sept. 10,1956, p. 104.
  13. Rosenberg, M., and R. J. Tailleur, "Increased Drill Bit Life Through Use of Extreme Pressure Lubricant Drilling Fluids," AIME Paper 1152-G, Presented Houston, Oct. 1958.
  14. Pigott, R. J. S., "Mud Flow in Drilling," API Drilling and Production Practices, 1941, p. 91.
  15. Hall, H. N., Thompson, H. and F. Nuss, "Ability of Drilling Mud to Lift Bit Cuttings," Trans. AIME, Vol. 189, (1950), p. 35.
  16. MacDonald, G. C., "Transporting Rotary Bit Cuttings," World Oil, Apr. 1949, p. 114.
  17. Williams, C. E., Jr., and G. H. Bruce, "Carrying Capacity of Drilling Muds," Trans. AIME, Vol. 192, (1951), p. 111.
  18. Gray, G. R., Neznayko, M., and P. W. Gilkeson, "Some Factors Affecting the Solidification of Lime-treated Muds at High Temperatures," API Drilling and Production Practices, 1952, p. 73.
  19. Watkins, T. E., and M. D. Nelson, "Measuring and Interpreting High-Temperature Shear Strengths of Drilling Fluids," Trans. AIME, Vol. 198, (1953), p. 213.
  20. O'Brien, T. B., "Formulation and Use of Sea-water Muds,"AP7 Drilling and Production Practices, 1955, p. 86.
  21. Perkins, H. W., "A Report on Oil-Emulsion Drilling Fluids," API Drilling and Production Practices, 1951, p. 349.
  22. Lummus, J. L., Barrett, H. M., and H. Allen, "The Effects of Use of Oil in Drilling Muds," API Drilling and Production Practices, 1953, p. 135.
  23. Lummus, J. L., "Multipurpose Water-in-Oil Emulsion Mud," Oil and Gas Journal, Dec. 13, 1954, p. 106.
  24. Nelson, M. D., Crittendon, B. C., and G. A. Trimble, "Development and Application of a Water-in-Oil Emulsion Drilling Mud,"API Drilling and Production Practices, 1955, p. 235.
  25. Bugbee, J. M., "Lost Circulation — A Major Problem in Exploration and Development," API Drilling and Production Practices, 1953, p. 14.
  26. Goins, W. C., Jr., Weichert, J. P., Burba, J. L., Jr., Dawson, D. D., Jr., and A. J. Teplitz, "Down-the-hole Pressure Surges and Their Effect on Loss of Circulation," API Drilling and Production Practices, 1951, p. 125.
  27. Cardwell, W. T., Jr., "Pressure Changes in Drilling Wells Caused by Pipe Movement," API Drilling and Production Practices, 1953, p. 97.
  28. Ormsby, G. S., "Calculation and Control of.Mud Pressure in Drilling and Completion Operations," API Drilling and Production Practices, 1954, p. 44.
  29. Goins, W. C., Jr., "How to Combat Lost Circulation," Oil and Gas Journal, June 9, 1952.
  30. Messenger, J. U., and J. S. McNiel, Jr., "Lost Circulation Corrective: Time Setting Clay Cement," Trans. AIME, Vol. 195, (1952), p. 59.
  31. Shumate, H. J., "Lost Circulation — Its Causes and What to Do About It," Oil and Gas Journal, Oct. 18,1951.
  32. Howard, G. C., and P. P. Scott, Jr., "An Analysis and the Control of Lost Circulation," Trans. AIME, Vol. 192, (1951), p. 171.
  33. Coberly, C. J., "Selection of Screen Openings for Unconsolidated Sands," API Drilling and Production Practices, 1937, p. 189.
  34. Furnas, C. C., "Mathematical Relations for Beds of Broken Solids of Maximum Density," Industrial and Engineering Chemistry, Vol. 23, Sept. 1931, p. 1052.
  35. Anderegg, F. O., "The Application of Mathematical Formulae to Mortars," Industrial and Engineering Chemistry, Sept. 1931, p. 1058.
  36. Bobo, R. A., and R. G. Hoch, "Mechanical Treatment of Weighted Drilling Muds," Trans. AIME, Vol. 201, (1954), p. 93.
  37. Scott, P. P., Jr., and J. L. Lummus, "Cyclones Save Barite, Reject Clay Solids," Oil and Gas Journal, Oct. 8 and Oct. 15, 1956.
  38. Reed, R. M., "Air Drilling with Foam Combats Water Influx," The Petroleum Engineer, May 1958, p. B-57.
  39. Nicolson, K. M., "Air and Gas Drilling," Fundamentals of Rotary Drilling. Dallas, Texas: The Petroleum Engineer, 1954, p. 86.
  40. Adams, J. H., "Air and Gas Drilling in the McAlester Basin Area," API Paper no. 851-31-N. Presented Tulsa, Apr. 1957.
  41. Fuller, L. S., "Hazards of Drilling with Natural Gas," World Oil, Jan. 1954.
  42. Bobo, R. A., Ormsby, G. S., and R. S. Hoch, "Phillips Tests Air-Mud Drilling," Oil and Gas Journal, Jan. 24, 1955.
  43. Weiss, W. J., Graves, R. H., and W. L. Hall, "A Fundamental Approach to Well Bore Stabilization," The Petroleum Engineer, Apr. 1958.

Chapter I

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